The present disclosure relates generally to an apparatus and method for reducing cross-talk between capacitive sensors. More particularly, the present disclosure relates to reducing cross-talk between capacitive sensors used in plumbing applications such as electronic faucets, electronic toilets and related electronic accessories such as electronic soap dispensers, for example.
Electronic faucets are often used to control fluid flow. Electronic faucets may include proximity sensors such as active infrared (“IR”) proximity detectors or capacitive proximity sensors. Such proximity sensors are used to detect a user's hands positioned near the faucet, and turn the water on and off in response to detection of the user's hands. Other electronic faucets may use touch sensors to control the faucet. Such touch sensors include capacitive touch sensors or other types of touch sensors located on a spout of the faucet or on a handle for controlling the faucet. Capacitive sensors on the faucet may also be used to detect both touching of faucet components and proximity of the user's hands adjacent the faucet.
Capacitive sensors are also used as flush actuation sensors, tank fill sensors and bowl overflow sensors in electronic toilet applications. In addition, capacitive sensors are used on plumbing related accessories such as liquid soap dispensers, for example.
In capacitive sensing applications, other components located near the electronic faucet may have unintended effects on the output signal from the capacitive sensors. For instance, a user touching a metal sink basin may induce a false capacitive signal at the capacitive sensors. Changes that occur below a sink deck may also cause false readings at the capacitive sensors.
In other capacitive sensing applications, multiple capacitive sensors coupled to the same controller may produce cross-talk between the capacitive sensors and therefore also have unintended effects on the output signals from the capacitive sensors. For example, large changes in capacitance of a first capacitive sensor may cause changes in capacitance of a second capacitive sensor large enough to trigger a false sensing event in the second capacitive sensor. Conventional sensing applications use complicated software algorithms to try to reduce the effects of cross-talk between adjacent capacitive sensors.
In one illustrated embodiment of the present disclosure, a sensing apparatus includes a first capacitive sensor coupled to a first component, and a second capacitive sensor coupled to a second component. The second capacitive sensor includes a sensing electrode, a first sense wire coupled to the electrode, and a second sense wire spaced apart from the electrode. The sensing apparatus also includes a controller coupled to the first capacitive sensor and to the first and second sense wires of the second capacitive sensor. The controller is programmed to determine a difference signal between first and second output signals received from the first and second sense wires of the second capacitive sensor, respectively, to reduce an effect of cross-talk from the first capacitive sensor on the second capacitive sensor. The controller is also programmed to analyze the difference signal to detect a change in capacitance of the second capacitive sensor caused by an event.
In another illustrated embodiment of the present disclosure, an electronic toilet includes a toilet tank configured to receive and hold water from a water supply therein, at least one capacitive sensor located within the toilet tank, a toilet bowl in fluid communication with the toilet tank, and a bowl overflow capacitive sensor coupled to the toilet bowl a location above a normal water fill level of the toilet bowl. The bowl overflow capacitive sensor includes a sensing electrode, a first sense wire coupled to the electrode, and a second sense wire spaced apart from the electrode. The electronic toilet also includes a controller coupled to the at least one capacitive sensor in the toilet tank and to the first and second sense wires of the bowl overflow capacitive sensor. The controller is programmed to determine a difference signal between output signals received from the first and second sense wires of the bowl overflow capacitive sensor to reduce the effect of cross-talk on the bowl overflow capacitive sensor. The controller is also programmed to analyze the difference signal to determine when a water level in the toilet bowl is above the normal water fill level of the toilet bowl.
In yet another illustrated embodiment of the present disclosure, an electronic soap dispenser includes a dispensing head including an outlet, a pump operably coupled to a soap storage reservoir to pump the liquid soap from the soap storage reservoir to the outlet of the dispensing head, and a capacitive sensor operably coupled to the dispensing head. The capacitive sensor includes an electrode, a first sense wire coupled to the electrode, and a second sense wire spaced apart from the electrode. The electronic soap dispenser also includes a controller coupled to the first and second sense wires of the capacitive sensor. The controller is programmed to receive first and second output signals the first and second sense wires, respectively, to determine a difference signal from a difference between the first and second output signals, and to analyze the difference signal to detect actuation of the capacitive sensor by a user, and to selectively actuate the pump to dispense soap from the outlet of the dispensing head in response to a detected actuation of the capacitive sensor by the user.
Additional features and advantages of the present invention will become apparent to those skilled in the art upon consideration of the following detailed description of the illustrative embodiment exemplifying the best mode of carrying out the invention as presently perceived.